Methods and apparatus for producing sand molds

ABSTRACT

The provision of sand casting molds by means of at least one mold frame, at least one pattern plate, at least one press die movable vertically relative to the pattern plate, a mold-sand chamber located opposite the press die, a pneumatic mold-sand filler device which by means of a superficial pressure gas load on a mold-sand volume located in the mold-sand chamber moves at least a part of the mold-sand volume into the mold frame area through openings in the press die, said mold-sand volume beng automatically pre-compacted in said mold frame area by the kinetic force of such movement, and by moving the press die towards the pattern plate there is a re-compacting of the sand, and the released finished mold is moved by a conveying means to a casting pit and a knock-out point. The mold-sand filler device is operated in a manner so that the mold-sand volume in the sand chamber is evenly pentrated with pressurized gas and also is superficially loaded with pressurized gas for moving the volume into the mold frame area. A part of the sand filling which has been moved into the mold frame area is forced back through the press die openings into the sand chamber during re-compacting effected by the press die. The finished molds are moved along a conveying track by means of force impulses which are directed generally horizontal in the conveying direction, with the impuses each affecting intermittently the molds via friction over part areas of the mold surface thereby overcoming the friction between the mold bottom areas, which rest on certain support areas of the conveying track, and these bottom support areas.

United States Patent [191 Buhler [451 Apr. 30, 1974 METHODS AND APPARATUS FOR PRODUCING SAND MOLDS [76] Inventor: Eugen Buhler, Weg zur Walk 96,

Burtenbach, Kreis, Gunzburg, Germany [22] Filed: Jan. 29, 1973 [21] Appl. No.: 327,773

Related US. Application Data [60] Continuation-impart of Ser. No. 105,067, Jan. 8,

1971, Pat. No. 3,744,549, which is a division of Ser.

No. 753,640, Aug. 19, 1968, Pat. No. 3,556,196.

Primary Examiner-J. Spencer Overholser Assistant Examiner-John E. Roethel Attorney, Agent, or Firml-lolman & Stern [57 ABSTRACT The provision of sand casting molds by means of at least one mold frame, at least one pattern plate, at least one press die movable vertically relative to the pattern plate, a mold-sand chamber located opposite the press die, a pneumatic mold-sand filler device which by means of a superficial pressure gas load on a mold-sand volume located in the mold-sand chamber moves at least a part of the mold-sand volume into the mold frame area through openings in the press die, said mold-sand volume beng automatically precompacted in said mold frame area by the kinetic force of such movement, and by moving the press die towards the pattern plate there is a re-compacting of the sand, and the released finished mold is moved by a conveying means to a casting pit and a knock-out point. 0

The mold-sand filler device is operated in a manner so that the mold-sand volume in the sand chamber is evenly pentrated with pressurized gas and also is superficially loaded with pressurized gas for moving the volume into the mold frame area. A part of the .sand filling which has been moved into the mold frame area is forced back through the press die openings into the sand chamber during re-compacting effected by the press die.

The finished molds are moved along a conveying track by means of force impulses which are directed generally horizontal in the conveying direction, with the impuses each affecting intermittently the molds via friction over part areas of the mold surface thereby overcoming the friction between the mold bottom areas, which rest on certain support areas of the conveying track, and these bottom support areas.

36 Claims, 9 Drawing Figures Elan- L483 PATENTEBAPR 30 I974 SHLH l OF A 1 METHODS AND APPARATUS FOR PRODUCING SAND MOLDS This application is a continuation-in-part of my copending application Ser. No. 105,067 filed Jan. 8, I971, now U.S. Pat. No. 3,744,549, which is a division of Ser. No. 753,640 filed Aug. 19, 1968, now U.S. Pat.

No. 3,556,196 dated Jan. 19, 1971.

BACKGROUND OF THEINVENTION for preparing sand molds.

One of the greatest difficulties is obtaining an always evenly good density or hardness of the forms, as one attempted to secure, for example, by means of preliminary shaking or jolting and re-pressing of the forms and placed into the mold frame, shaking, during the pressing step, by means of utilizing multi-press-dies and other measures. It is thus the object of the present in vention to be able to provide sand molds with a hardness which, for example, in the form areas outside the pattern contours, are nearly as hard as, for example, the form areas which prevail adjacent the most'elevated pattern areas.

The above short description of the prior art methods has various disadvantages. For example, the noise prevailing during the shaking is very loud and disagreeable; furthermore, the equipment for the operation of the respective methods is often very costly, which holds true 'especiallyfor multi-press-dies and, in addition, none of the prior art methods is universally applicable.

The utilization of prior art methods especially for the automated flaskless molds, preferably in the so-called match plate system, is either very difficult or is not at all possible. This is true already for normal flaskless molds since the device which pulls the frame from the finished mold produces difficulty, and still more so in the utilization of the match plate system in which an upper mold section and a lower mold section are formed simultaneously, as known.

' With regard to the match plate system, U.S. Pat. No. 3,229,336 describes a proposal in which the molding sand is introduced pneumatically into the moldframe area by-means of laterally placed slits in the mold frame. in such a method, there result, however, in addition to a strong'wear on the form, also difficulties with respect to .density, and especially disadvantageous is the fact that the areas situated in the area sheltered from the draft of the mold-sand inlet behind the form, obtain a substantially lesser hardness than the form areas situated in front of the mold. The same cannot be corrected even by means of slidable press dies since hereby especially only those mold areas can be redensifiecl which are adjacent the most raised mold areas, while these mold areas situated near the separating line and outside the pattern contour are only partially affected by such a re-pressing. A further reason for the dissatisfying pre-densification of the mold sand which is placed into the mold frame area during the introduction of the mold sand through the lateral slits in the mold frame, is in the re-routing of the sand-gas-flow, whereby the speed of the mold sand is reduced. The results are then again sand molds having strongly varying hardnesses and densities at various areas of the mold.

Disclosed in the applicant's above-mentioned U.S. Pat. No. 3,556,196, is a method for preparing horizontally separated flaskless sand molds inwhich there is provided an actual and practically feasible improvement over the prior art match plate system. According to this method, a mold apparatus being provided with a horizontal, horizontally-displaceable, double sided pattern plate, upper and lower vertically displaceable mold frames, upperand lower vertically displaceable press dies, an upper sand chamber arranged above the upper press die, a lower sand chamber arranged below the lower press die, a pressure-gas plant provided with a control device which supplies the sand chamber, and a conveyor arrangement which is in synchronous operation with the movement of the pattern plate, the mold frame areas are closed at both sides by means of relative movements between the mold frames, the pattern plate and the press dies, after which, by means of superficial pressue-gas admission to the mold sand volumes, which prevail in each of the sand chambers, at least a part of the mold sand volumes are placed into the mold frame areas through the openings of the press dies, and are pre-densified therein by the kinetic forces of such movement, and are thereafter post-densificd by means of sliding the press dies towards the pattern plate, after which, through relative movements between the mold frames, thepattern plate and the press dies, the form is pushed out and is moved to the casting pit and removal point.

There result some difficulties also in this method especially with regard to the sealing of the mold frames towards the pattern plate as well as regarding the undesired dual-centering between thepress die and mold frame on the one hand and the mold frame and pattern plate on the other hand. Also, the desired evenly strong sand packing seems still to require improvement.

OBJECTS AND SUMMARY OF THE INVENTION The first object of the present invention is to provide a generally useable method for providing sand molds which, at most extensive automation permit, without substantial annoying noises, the production of molds with an even hardness over the entire mold area, whereby under the term evenly hard in the normal situation, the permissive variations of hardness should be understood to be about l0 to 15 percent at the most for the average hardness of the mold. At the same time, the above mentioned packing and centering difficulties should also be overcome and the latter is true especially for flaskless molds.

A further object of the present invention resides therefore in the application of this method during the flaskless forming, whereby a formerly unattainable optimization of the latter seems to be now obtainable. Such an optimization was prevented, in addition to the above-mentioned difficulties in the match plate system also by the following difficulties:

The space which of the available for the core insertion into the lower part ofthe mold in the position where the upper and lower mold frames and extended mold plate are separated from each other and the pattern plate is laterally moved into its inoperatve position, is very limited and the person placing the core must reach into this space and during the production of large molds must also bend into this space, and hence is subjected to hazards to a great extent. In addition, the time required for placing the core with regard to the operational process of the mold machine represents an undesirable time loss.

It is therefore a further object of the present application to make the inserting of the core as safe as possible and simultaneously to provide that the time span required to insert the core in view of the operating rhythm of the mold apparatus no longer represents a time loss.

ln the preparation especially of flaskless molds for forming purposes, trolley conveyors or link conveyors must be utilized for the transporting of the finished molds, which require extensive space, and are costly to manufacture, while the link conveyors during lengthy conveyor paths require their own motors, which motors must be synchronized again with the operational rhythm of the mold apparatus. The same holds true for endless steel bands which, in addition, are disadvantageous in that such bands are very sensitive to liquid.

iron. lf roller conveyors are used, then the finished molds must be placed on suppport planks, which again results in additional expense.

Moreover, during the production of flaskless molds, the finished molds must be reinforced during the transport in general by attaching so-called jackets or clamping plates. A special problem presented thereby in horizontally divided molds is the undesired staggering between the lower section of the mold and the upper section of the mold. This means that strict attention must be observed not only on the precise mutual centering of the sections which are movable vertically towards each other, but that the finished forms are carefully protected during their transport to the casting pit and knock-out point against theeffects of horizontal forces. Especially during the placing of incorrectly fitting jackets or clamping plates, for example, on unevenly dense or partially soft molds, there exists the danger that molds delivered by the mold apparatus obtain afterwards a backfill which is caused by the fact that during the placing of the jackets or clamping plates, the upper mold section is displaced somewhat horizontally relative to the lower part of the mold. A certain amount of protection during the transport of the molds would be provided by the forming of a socalled -gradation", Le, a mutually complimentary gradation of both mold sections running along the border of the separating line. This measure, however, requires that particularly the bordering areas of the mold sections have a substantial extensive and even hardness near the separating line. The desired optimation of the flaskless molds has thus also in this case the provision that the basic evenness of the mold density, or mold hardness. which is an object of the instant invention, may be realized indeed over the entire mold area.

This basic goal, being the object of the present invention, finds therewith most of all in the utilization of the invention in flaskless molds its natural supplementation in the further object to transport the finished molds in such a manner so that in the preparation of the mold in their transport, the advantages which can be obtained with the improved mold method are not lost.

It is a further object of this invention to transport the finished molds in the most protective manner to the casting pit and knockout point by means of a device which is inexpensive to manufacture, and economical in operation, insensitive to interferences, requiring lit- I 4 tle space, only low actuating forces, and is easily synchronized with the operational rhythm of the mold apparatus, without causing thereby a disadvantageous displacement of the molds.

Even though, as explained above, all objects of the invention are necessarily closely related to each other, these goals in themselves are of general importance for the technique of the mechanical production and provision of sand molds, so that also the individual hereinbelow described inventive processes in themselves, or in a different connection, are absolutely of substantial and individual inventive importance.

In view of reaching the above-mentioned goals, this invention contains in its most general concept firstly a method for producing sand molds by means of at least one mold frame, at least a single-sided pattern plate, at least a press die movable vertically relative to the pattern plate and a pneumatic filler device for the form sand which, by means of a superficial pressure gas load on a mold-sand volume in a sand chamber situated near the press die, moves at least a part of the form sand volume into the mold frame area through the openings of the press die, said form sand volume being thereafter compacted by moving the press die towards the pattern plate, and the finished form being pushed out is conveyed to the die pit and knock-out point, and this method being characterized by one or a plurality of the following characteristics:

a. The mold-sand is introduced into the mold frame area in flows which are evenly distributed over nearly the entire press die area, penetrating a substantial part of same, with the flows being substantially vertical thereto and along straight lines whereby, preferably, the pneumatic mold-sand filling device is operated in a two-stage manner so that in a first pressure stage the mold-sand volume being located in the sand chamber is interspersed with pressurized gas and in a second pressure stage the mold-sand volume is mainly being superficially subjected to pressure gas for the purpose of introducing it into the mold frame area;

b. A part of the sand filling which has been introduced into the mold-frame area is forced during the recompacting by means of the press die to return through the openings in the press die into the sand chamber.

0. The finished molds are transported along the conveyor track by means of force impulses being effective in a generally horizontal direction along the conveying track whereby the force impulses each affect intermittently the mold by means of friction over partial areas of the surface of the mold and thereby overcome the friction between areas of the underside of the mold which rest on certain supporting areas of the conveying track and these supporting areas.

There are offered three possibilities for performing the present inventive method, namely, the forming and casting with the use of mold-boxes, the forming and casting without mold-boxes and the flaskless forming and casting (match-plate system). Insofar as the inventive method is realized by utilizing forming and casting with mold-boxes or is realized by forming with moldboxes and casting without mold-boxes, the uniformly used term Mold frame" is to be understood in the sense of mold-box.

Preferably, during the present process the pneumatic apparatus for filling the sand into the mold is operated in atwo-stage manner so that the two pressure stages overlap timely.

Practically, the mold-sand volume which is in the sand chamber, is thereby additionally interspersed from its inside with pressurized gas, at least while being superficially subjected to pressure gas action.

In contrast to the prior art blowing and blasting method, there thus results during the inventive blasting of the form-sand an almost exclusively linear movement of the form-sand perpendicular to the press die plane and a simultaneous distribution over the entire press die area, whereby the kinetic energy is exploited to the greatest possible extent for the compression of the transported form-sand during the impact on the match-plate and mold. Such a high acceleration and thereby high final speed of the form-sand results from the inventive sudden superficial pressure action on the mold sand in the sand chamber due to the admission of transport gas via large cross-sections, whereby the simultaneous penetration of the sand volume with the transport gas by means of particular injection jets and therewith the Liquefaction of the form-sand prevents the forming of a crater and at the same time results in a reduction of the consumption of transport gas, which in turn reduces the compression-reducing puffer effects of the transport gas which flows into the moldframe area and has there to be again removed therefrom.

The sand packing is advantageously penetrated with pressurized gas during the recompacting which is'effected by means of the press die. The inventively proposed retreating of a part of the sand filling through the openings of the press dies into the sand chamber is thereby facilitated, which is an important requirement for the desired uniform density of the form-sand over allof the form areas.

During tests made in the past for the purpose of compressing the form sand by means of perforated press dies, due to known method there developed repeatedly jamming of the openings of the press dies.

A very important embodiment of the method represents its combination with the match-plate system, whereby a possibility is provided for the realization of producing large molds and the precise shaping of high forms of the molds which was formerly impossible to obtain with this system.

ln connection with the match-plate system, a preferred embodiment of the inventive method for manufacturing sand casting molds with at least one core is characterized in that prior to closing of the mold, the

bottom half of the mold is moved from the working space of the mold frame without a bottom support, a core is placed and the bottom half of the mold is then moved back into the working space of the mold frame.

In an improved embodiment of the inventive method, instead of moving the bottom half of the mold out of the working space of the mold frame, advantageously another identical prepared bottom half, into which a core has already been inserted, is moved into the working space of the mold frame. Either before or after the exchanging of the pattern the respective missing upper or lower half of the mold is post or prefabricated.

A further important characteristic of the method is that respective specific mechanical surface pressures are affecting the upper surface and at least two lateral surfaces of the mold located on the conveying track,

which adapt themselves widely to the contours of these surfaces.

The present invention comprises additionally an apparatus for performing the method in its most general form, which comprises: at least one mold frame; one movably arranged pattern plate employable at least on one side; at least one press die provided with outlet openinss and being movable vertically to the pattern plate; a sand chamber located opposite the press die; a mechanical charger for the sand chamber; and a pneumatic device supplying the same chamber with pressurized gas in a controlled manner; and a conveying track leading to a casting pit and knock out point; characterized in accordance with the invention in that, in addition to at least one duct for pressurized gas with a large cross-section for creating a sudden surface pressure gas action of the sand volume present in the sand chamber, there are also a plurality of ducts for pressurized gas of smaller cross-sections discharging into the sand chamber and effecting a penetration with pressurized gas of the sand volume located in the sand chamber.

The press die of the inventive device is constructed preferably in the shape of a grid in which the clearances in the grid constitute the outlet openings for the mold sand.

' A preferred embodiment of the present apparatus is characterized in that at least one part of the mold conveying track is constructed as a grid conveyor means provided with at least two mutually interspersing movable grids extending in the conveying direction, of which at lease one relative to the other executes a forward and backward movement in the conveying direction depending on the movement of the pattern plate, and is pressed onto the bottom half of the mold to be transported in such a strong manner, any time before moving in the direction of transport so that the friction which develops between this grid and the mold becomes greater than the friction between the other grid and the mold, while this grid obtains an impulse being directed away from the bottom area of the mold any time before the counter-movement of the grid against the conveying directon and this impulse being so strong that the friction between this grid and the mold becomes less than the friction between the mold and the other grid.

- The grid conveyor may be placed in seria with a nonactivated band conveyor serving as a cooling track for the already cast molds.

At least one part of the conveying track, as one improvement of the instant invention, can be slidably arranged transversely to the conveying direction relative to the mold machine, and there may be provided at least one additional such tranversely slidable conveying track.

Within the area of the conveying track, means may be provided which accompany the molds on their travel, whereby said means support at least two oppositely placed lateral surfaces of the mold and which during their placement on the molds automatically adjust to the contours of the molds.

Some embodiments of the inventive method are described hereinbelow in detail under reference to the attached drawings on the basis of a few preferred embodiments of the instant inventive apparatus; wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view in vertical section through a part of an apparatus embodying the invention which is suitable for forming and casting with the use of mold boxes as well as for forming with the use of a mold box and casting without a mold box;

FIG. 2 is a view in vertical section, on an enlarged scale, of one of the components shown in FIG. 1

FIG. 3 is a diagrammatic view in vertical section through a part of another embodiment of the present invention suitable for the flaskless forming of horizontally separated sand molds especially in accordance with the match-plate system;

FIG. 4 is a view partly in side elevation and partly in vertical section of a detail of an improved embodiment of the apparatus of FIG. 3;

FIG. 5 is a top plan view of the detail shown in FIG.

FIG. 6 is a diagrammatic view in side elevation and partly broken away of the apparatus illustrated in FIG. 3 with the associated inventive conveyor track;

FIG. 7 is a view taken along the lines VII-VII of FIG. 6, the view looking in the direction of the arrows;

FIG. 8 is a view similar to FIG. 7 in a different operational position of the components; and

FIG. 9 is a diagrammatic view in vertical section cut through a sand casting mold produceable with the apparatus inaccordance to FIGS. I and 2, with the sand casting mold being provided with a supporting means useable on the conveying track in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION The section of an inventive apparatus for accomplishing the present method in combination with moldboxes (FIG. 1) comprises generally a blasting and pressure-head A mounted in a fixed position, and a pattern plate E which is movable upwardly and downwardly relative to the head in accordance with the arrow I. The upward and downward movement of the pattern plate E may, for example, be effected by means of a pneumatic or hydraulic power drive provided with a piston rod E1. The preferably outwardly swingable pattern plate E can receive exchangeable patterns M and a mold or mold-frame C of prior art construction can be positioned on the plate E. The entire peripheral rim of the pattern plate E is extended vertically upwardly to provide a vertical sealing edge E2, along which vertical lateral edge C1 of the mold frame C, during the placement thereof, slides sealingly therealong. Additionally, the rim of pattern plate E is provided with a preferably non-encircling abutment E3 whose upper surface lies in the plane of the upper surface of the pattern plate E so that lower lateral edge C2 of the mold-frame C engages the abutment and thereby guarantees that the lower lateral edge C2 is located at the same height as the plane of the operational area of pattern plate E.

The head A comprises generally a sandchamber a which is surrounded by a pressurized gas distribution casing or manifold Al, A2, which, by means of a shutter slide A3 is sealed in a sand and gas-tight manner, opposite a prior art (not illustrated) sand-supplying device which is located thereabove, and is sealed at its bottom by a press die B defined by a grid or grating. The spaces between the bars of the grid are at least 35 mm. wide. The sand-shutter slide A3, for example, may be slid pneumatically or hydraulically in a manner so that it frees the upper opening of the sand-chamber a" so that chamber may be filled with mold-sand from a sand tank (not shown).

The gas distribution casing is divided into separate upper and lower gas distribution chambers Al and A2. The upper gas-distribution chamber Al is connected to a pressure gas pipe 21 having a large cross-sectiion while the lower gas distribution chamber A2 is connection with a pressure gas pipe 22 having a smaller cross section. The upper gas distribution chamber Al is, in its uppermost part, connected with the uppermost section of sand chamber a" by means of comparatively wide passage slots 1, and below the slots 1, it is connected with the sand chamber a by means of a plurality of passage jets 2 which are also distributed over the entire circumference of the sand chamber a. The lower gas distribution A2 is connected with the sand chamber a also by means'of a plurality of passage jets 3. Additionally, the lower zone of the said chamber a is provided with a plurality of gas distribution transverse pipes A4 which are connected to the lower gas distribution chamber A2 as illustrated in FIG. 2, the transverse pipe A2 is provided with a configuration similar to an olbesto and is formed with a plurality of passage jets 4 which are distributed over the entire length of the pipe. The jets 4 are effectively arranged in a row which extends parallel to the axis of the pipe and rows of shutters 5 are arranged in the inside of the pipes and are placed always in front of the respective rows of jets and in parallel thereto. The shutters 5, one one hand, allow a predetermined amount of gas to flow out through the jets 4, and on the other hand, prevent the mold sand moving through the jets 4 into the interior of the pipes A4, which would block the pipe after a period of time. Similar shutters may also be arranged in front of the jets 2 and 3 of the gas-distribution chambers Al and A2.

The lower end of the second chamber a" is framed by a vertically slidable sand-frame K, and the sandframe K is pressed downwardly by means of springs 6. The springs 6 bear at their upper ends against a fixed section of the sand-chamber and at their lower ends against an inner flange provided on a somewhat outwardly extending rim forming the lower end of the sand chamber, with the press die B being affixed thereon. The sand frame K is provided with a lower outer flange to which is attached a sealing means 7. The form of this lower outer flange of the sand frame K coincides precisely with the form of the upper edge of the mold frame C so that during the upward movement of the pattern plate E, which carries mold frame C, the upper edge of the mold frame C is in sealing contact with the sealing means 7 of the sand frame K.

The pressure gas pipes el and e2 are connected in a manner known in the prior art (not shown) to a pressure gas system for effecting the filling of mold sand into the mold frame C. The pressure gas system may be a dual-stage operational system and in a first pressure stage acts upon the pressure gas pipe e2 of the smaller diameter and in a second pressure stage upon the pressure gas pipe e1 of larger diameter, whereby both pressure phases may overlap themselves timely.

Ventilation bore holes 8 and 9 are arranged in the mold frame C and the pattern plate E respectively.

The operation apparatus for producing sand mold, as illustrated in FIG. I is as follows:

It may be assumed that pattern plate E is placed in a lower position (not shown in the drawing) in which it is located at a sufficient distance from the sand-filling frame K which has been forced into its lowermost position by means of springs 6, so that a mold frame C may be disposed upon the pattern plate which carries one section of the mold whereby the pattern plate is preferably swiveled outwardly. Both pressure gas pipes el and e2 are pressureless.

While the mold frame C is being placed on the pattern plate E, the shutter slide A3 is opened and a predetermined volume of mold sand is admitted into the sand chamber a", filling the same to the extent approximately shown in FIG. 1. After closing of the shutter slide A3, the pattern plate E is moved inwardly and upwardly until the upper edge of the mold frame C abuts sealingly against-the sealing means 7 of the frame K under compression of the spring 6.

The prior art pneumatic mold sand filling device (not shown) is now operated so that initially the pressure gas pipe 22 with the smaller diameter is loaded with pressure-gas in a first pressure stage. The pressurized gas arrives therefrom into the lower gas distribution chamber A2 and into the gas distribution transverse pipes A4 and flows through the jets 3 or 4 as well as from the outside and from the inside into the mold sand volume which is present in the sand chamber. This causes the mold sand volume, expecially in its lower portion, to be entered from all sides closely by the pressure gas and begins, so-to-speak, to flow. Thereafter, the gaspipe a! with the larger diameter is then suddenly loaded with pressurized gas, so that also promptly a large volume of pressurized gas moves from'the upper gas distribution chamber A1 into the free space above the mold sand volume present in the sand chamber, and simultaneously flows by means of the jets 2 from the chamber Al especially into the upper half of the sand volume located in the sand chamber af and enters also this upper half, particularly in v the bordering areas. The

sand volume located in the sand chamber, having now become flowable in its entirely, as a result thereof, is now suddenly forced downwards,- due to the excess sudden pressure, by means of the pressurized gas entering through the wide passage slots I, and is now blasted through the spaces between the grid bars of the press die B, into the mold space of the mold frame C, whereby the used air can find exit via the ventilation boreholes 8 or 9 provided in the mold frame C and in the plate E.

After completion of this second pressure stage, i.e., after blocking of the pressure gas admission via the pressure gas pipe with the larger diameter e1, the largest part of the sand volume located in the sand chamber a" has thus been blasted into the mold space which is delimited on the bottom by the pattern plate E or the pattern M, at the sides by the mold frame C and at the top by the frame K and the press die B, whereby the sand filling located in the mold space, is already very favorably compacted. The pressure gas pipe'22 with the smaller diameter and therewith the lower gas distribution chamber A2 and gas distribution transverse pipes A4 are still under pressure so that the mold sand volume which remains in the sand chamber a" is still being penetrated with pressure gas by means of the jets 3 and 4.

The pattern plate E is now pushed further upwardly .by a small degree so that also the mold frame C and the frame K relative to the fixedly positioned sand chamber a and the press die B, which define the bottom closing of same, are moving vertically upwardly. The press die B which so-to-speak, functions as a counter die, due to its reactional force, enters thus to some extent into the mold space and effects a further compacting of the already pre-compacted sand-filling located therein. Especially the mold sand which is located above the uppermost pattern points is thereby forced to move back again into the sand chamber a by means of the openings which are provided between the grid-bars of the press die B. As a result thereof the sand filling which is located in the mold frame C receives an almost even compactness distributed over the entire mold space, and thereby obtains an almost evenly extensive hardness. This returning of the mold sand from the mold space into the sand chamber a is simplified by the fact that the sand remaining in the sand chamber a is still being pentrated with pressurized gas in the first pressure stage, which timely overlaps the second pressure stage.

If now, the admission of pressure into the pipe e2 having the smaller diameter, is concluded, and the pattern plate E is moved downwardly, then the new completed mold releases itself from the press die B and the sand filling frame K is again moved downwardly, until it abuts the press die B, by means of the springs 6. The mold frame C can then be lifted together with the mold from the pattern plate E and moved by means of a conveyor track towards its further utilization.

Tests have shown that in the above-described simple manner, it is possible to produce sand molds whichhave formerly unobtainable evenness and hardness.

With reference to FIG. 3, there is disclosed the combination of the above-described method with the prior art match-plate system. Sections of the apparatus illustrated in FIG. 3, which are of identical construction or which have identical functions, are provided with the respective parts of the device illustrated in FIG. 1. They are identified with identical reference numerals or reference letter and, where required,vshow respective subscripts.

Apparati which function according to the matchplat e system, may, for example, comprise, a mold machine with a horizontal, horizontally slidable, on both sides employable pattern plate; upper and lower vertically slidable mold frames; upper and lower vertically slidable press dies; an upper sand chamber arranged above the upper press die; a lower sand chamber arranged below the lower press die; a mold sand tank connected with both sand chambers; and a pressure gas device provided with control means and which supplies pressurized gas to the sand chambers.

FIG. 3 illustrates a flaskless mold apparatus of such a construction only in part and only in so far as substantial characteristics of the inventive method are realized therein. A

The flaskless mold machine which is partially illustrated in FIG. 3 is provided with an upper press die Ba, a lower press die (not shown), an upper mold frame Ca and a lower mold frame Cb. The vertical displacement of both mold frames'Ca and Cb is accomplished in a prior art manner by pressure means activators (not shown). A pressure means activator Fa and an identical pressure means activator (not shown) serve for the vertical displacement of both press dies. The pressure activator means representing prior art, in cross section includes circular cylinders and annular pistons which are slidably arranged therein, with their piston rods being circular in cross section and forming simultaneously telescopic extensions of the associated annular ring cylinders. A hollow pattern plate D is horizontally slidable also in a prior art manner.

FIG. 3 illustrates the mold machine in a so called filling position, in which both mold frame Ca and Cb are placed on the pattern plate D.

The fixed annular cylinder of the upper pressure means activator Fa in combination with its cylindrical affixed piston rod, cylindrical upper pressure gas distribution chamber Al and the upper press die Ba define an upper sand chamber a while the fixed ring cylinder of the lower pressure means activator (not shown) in combination with its cylindrical piston rod, a fixed cylindrical lower pressure gas distribution chamber and the lower press die in a similar manner define a lower sand chamber. Both sand chambers can be filled with mold sand from a mold sand tank (not shown), in the prior art manner, and such is therefore not illustrated. The two pressured gas distribution chambers and the two sand chambers are connected in a similar manner to a pressure gas supply system as described above in connection with FIG. 1. The inside of the pattern or match plate D is connectable to the suction-side of an air pump, and, if required, is also connectable to its pressure side. If both sand chambers are filled with mold sand, then this mold sand, in the manner described in connection with FIGS. 1, can be promptly stressed with pressurized air, and can thereby be forced into the mold frame space of the two mold frames Ca by means of the grid openings which are located in the press dies, while the mold sand is simultaneously precompacted. The inside of the hollow pattern plate D may be evacuated, so that the pressurized air which enters the mold frame areas together with the mold sand is able to enter the inside of pattern plate D by means of ventilation boreholes 9 which are provided in the two plate areas, and removed therefrom by means of the air pump. Subsequently, the two press dies are moved in a direction towards the pattern plate D through activation of the two pressure means activators and the mold sand which is present in the mold frame areas in a pre-compacted condition, is thereby again compacted so that two solid and dense mold sections are formed which are able to sustain the substantial requirements.

The finished molds are then moved to a casting pit and knock-out point by means of a conveyor track.

Also, in the embodiment of an apparatus for the performance of the present method, as illustrated in FIG. 3, vertical sealing edges D2a and D2b are prvided between the plate D and the rim-edges of the mold frames Ca and Cb facing the pattern plate D with the sealing edges D2a and D2b being adapted to each other so that the mold frame edges Dla or Dlb, during the placement of mold frames Ca or Cb onto the pattern plate D sealingly overlap above the pattern plate edges D2a or D2b. This will not only accomplish an effective sealing of the mold frames areas in view of the pattern plate D and therewith provide for an effective air distribution, but will, at the same time, prevent the requirement of cleaning especially the upper pattern plate area after each molding as is the case in prior art methods,

to remove the deposits of sand nests between the mold frame rim edges and the pattern plate surface area, since such sand nests would prevent a sealing between the pattern plate and mold frame. By means of this inventive arrangement, it is also possible for the mold frames Ca and Cb with regard to the pattern plate D to be automatically precisely centered which is an important factor in avoiding a displacement of the mold sections to be produced.

As may further be seen from FIG. 3, the pattern plate D is also provided with an impact rim E3.

In order to prevent a so-called double-fitting between the match plate D and the mold frames Ca and Cb on one hand and the mold frames and press dies on the other hand, the two press dies are formed by two discs 10 and 11, (FIG. 3) which are connected in parallel to each other and are laterally slidable, whereby the rim of disc 11 which faces the mold frame areas is sealingly guided in the mold frames Ca or Cb, while the rim of the disc 10, facing away from the sand chamber, is provided with a lateral clearance to the mold frame Ca or Cb. This results, on one hand, in a precise sealing between the respective press die and the associated mold frame and on the other hand prevents a double-fitting which could result in axial errors and interferences during the mechanical operation.

The upper press die is, of course, provided with means by which the lower press die disc 11 is hangingly attached to the upper press die 10 and is thus prevented from falling downwardly.

As previously mentioned, difficulties result especially in machines for performing the match plate system in connection with the core-insertion. In order to remove such difficulties the present invention proposes that in such machines, the lower mold frame Cb be laterally outwardly movably arranged. An embodiment of such an arrangement of the device as illustrated in figure 3 is disclosed in FIGS. 4 and 5. In order to enable the lower mold frame Cb to be laterally outwardly movable, the lower press die Bv, must be able to move out of the lower mold frame downwardly, as indicated in FIG. 4.

As the most simplified embodiment is the possibility of moving the lower mold frame Cb horizontally laterally from the operational area of the mold frame, after the press die has been removed. It is thereby considered that the lower form-half which is located in the mold frame area of the lower mold frame Cb has sufficient stability so that it is able to solidly adhere in itself as well as also in its lower mold frame. If the lower mold frame Cb is laterally pushed out, then the core insertion outside the mold machine can be accomplished without endangering the person charged with this task, and, after the core is inserted, the lower mold frame Cb is again pushed back into the operation position of the mold frame, and the mold may be closed in the usual manner. Such an embodiment of the present invention thus provides for an increased safety feature for the personnel, but it does not provide for time-saving with regard to the insertion of the core in view of the working rhythm of the mold machine.

In accordance with the preferred embodiment of the invention as shown in FIGS. 4 and 5, two lower mold frames Cb are combined to fonn a multi-arrangement so that in combination they comprise a rotary member 12 which is swingable in a horizontal plane by means of a vertical axle, 13. This arrangement insures that upon a lower mold frame Cb being located in the operation space of the mold frame simultaneously the other lower mold frame Cb is located outside the operation space of the mold frame. In this manner, it becomes possible that a lower mold half which is already provided in the one rotating section with the core already inserted into the lower mold section, is placed into the operational space of the mold frame of the machine, and to permit the continuation of the working rhythm of the machine, while simultaneously, without endangering the-operating personnel, and without timeloss regarding the working process of the mold machine in placing a core into the lower mold half which is located outside.

As may be seen from the above, the utilization of the earlier described inventive methods and inventive apparatus, in combination with mold-machines of most variable principles and especially also with mold machines operating according to the match plate system, makes it possible to produce sand-casting molds mechanically, which along all areas of the mold are provided with a substantially equal hardness, density and compactness. The especially inventive structure of the apparatus makes it also possible to manufacture horizontally divided flaskless sand molds of a high-accuracy of fit and practically without a mutual displacement of the two mold halves. Regarding the final product, namely, regarding the finished cast piece, the improvements resulting in this way would be meaningless if care would not also be given that the high stability and high precision of the producable molds due to the present invention is not subjected to damaging influences on the track from the mold-machine to the casting pit and knock-out point, whereby such influences would des tory the result of the inventively secured improvement with regard to the manufacturing process.

Accordingly, it is a necessary further object of the instant invention to secure a protective and smooth, and precisely with the rhythm of the mold machine coordinated transport of the finished molds to the casting pit and knock-out point.

This is obtained in that at least a part of the moldconveying track is constructed as a grid-conveyor with at least two oppositely penetrating and in the conveying direction moving grids, of which at least one, relative to the other, performs a forward and backward movement in the conveying direction, whereby the grid an-y time before its movement in the conveying direction is pressed so hard onto the bottom area of the mold to be transported that the friction which develops between the grid and the mold becomes greater than the friction between the other grid and the mold, while it receives an impulse which is directed always away from its movement counter to the conveying direction, with the impulse becoming so strong that the friction existing between the same and the the molds becomes less than the friction existing between the molds and the other grid. The friction values, of course, can also receive zero-values, however, an increase and decrease of the friction values in the presently described manner is to be preferred.

Such grid-conveyors, are known in prior art and are extensively utilized, for example, in metallurgical plants for conveying red-hot casting blocks or red-hot billets. For the above mentioned reasons, the inventively utilized grid conveyor is described below with reference to FIGS. 6 to 8 only insofar as it deviates from the prior art constructions. As a matter of known grid conveyors where the molds are mutually losingany contact with two reciprocating grids interspersing each other.

The movable grid of such a grid conveyor is shown by dotted lines in FIG. 6 and is indicated with reference numerals 14. Its movement which is also known in the prior art and which results, for example, from eccentric drives in combination with vent holes lever systems, is indicated by full lines as a vector-parallelogram and is identified by 15, in which the vertical strokes are drawn in a greatly exaggerated manner, while the size of the horizontal stroke which complies with the length of the respective finished mold which is to be transported, is drawn in accordance to scale. It is considered that the molds which are to be transported, and which are identified G in FIG. 6 should be transported in a tight series formation so that their frontal areas contact and support each other. The casting pit is diagrammatically indicated in FIG. 6 by a dotted line by means of a casting pan and identified H.

Even though the instant invention comprises also the application of the prior art grid-conveyors used in metallurgical plants, in combination with the transport of sand-casting-molds, it is obvious that for a really pro tective conveying of the molds the pure acceptance of the prior art principle on the conveying track is not sufficient. In a further improvement of the instant invention, such a conveyor track is therefore characterized in that spring-members are arranged between the gridbars of the conveyor and other supporting constructional elements of the conveyor, whereby the resilient force with regard to weight and dimensions of the molds which are to be transported, and with regard to the dimensions of the molds which are to be transported, and with regard to the dimensions of the grid bars and the size of the movement impulse of the moved grid towards the moved molds, or away therefrom, is measured in a manner so that the specific pressures required between their lower areas and the upper areas of the grids, with reference to conveying or not conveying of the molds which will be transported, vary in general symmetrically by an average value which complies with the mold-weight plus a respective additional weight which is placed on the molds.

Such an arrangement is now described in detail in FIGS. 7 and 8, showing a cross section through the conveying track as illustrated in FIG. 6, in various operation conditions. The grid bars of the movable grid are identified 16, while the other grid bars are identified 17. As can be seen, the grid bars 16 as well as the grid bars 18 are covered with rails 18 which are U-shaped or channel-shaped in cross-section, and which cover the entire length of the grid-conveyor and rest on the bottom area of the molds to be moved with their upper areas which form the U-shaped cross-pieces. Spring means 19 are arranged between the movable bars 16 and the associated coverrails 18 while spring means 20 are arranged between the fixed bars 17 and the associated cover-rails 18. These spring-means may be either helical springs or plate springs. For the adjusting or changing of the spring force, thereare provided suitable means such as, for example, displaceable intermediate wedges which are inserted between the bars and the springs (not illustrated). In the same manner it is also possible to provide means (not shown) for changing the vertical stroke of the bars 16. FIG. 7 shows the bars 16 in their uppermost position and FIG. 8 in their lowermost position, and in which figures the scale of height is exaggerated. In their uppermost position, as shown in FIG. 7, the movable bars 16 are moved in the direction of the transport by the preferably also adjustable horizontal conveying track, while they are pulled back in the lowered position shown in FIG. 8 by the equal course in longitudinal direction counter to the transport direction, which, for example, may be accomplished by means of a pressure means activator, affecting a cross-piece which connects all of the bars 16. In the embodiment shown in FIG. 6, the push-out stroke of the mold machine and the conveying-thrust of the bars 16 are coordinated in such a way that the molds which are located on the conveying track abut each other with their front section and thereby support each other. In deviation thereto, the knock-out stroke of the mold machine and the conveying stroke of the bars 16 may be coordinated in a manner such as to provide a mutual frontal distance of about 0.5 mm between the molds G on the conveying track.

According to a different embodiment of such a conveying track, the bars 17 can also be movable, and in which case, the operation of the conveying track is such that respectively between the working stroke of one grid and the working stroke of another grid there exists a rest-position.

The inventive type of the mold-transport on the conveyor track, expecially constructed by means of the above-described manner, has the advantage that for once there is provided the safest possible transport of the molds G and for the other, abrupt shocks into any direction are prevented. A special advantage is provided by the fact that the molds G which are to be moved abut with their bottom areas practically always with an almost specific area-pressure onto all bars, and these even area-pressures are subjected to only very unimportant variations during the alternating transition from the grid bars of the movable grid to those of the affixed grid or reverse within the rhythm of the movement of the movable grid, while these variations swing about a constant average value. Thus, there is no lifting off of a grid bar from the bottom area of the molds G which are being transported.

As indicated in FIG. 6, a non-actuated bandconveyor I may be placed in seria to the grid-conveyor of the conveying track behind the casting pit H to function as a cooling-course. A steel band conveyor may be utilized for this purpose since the casting piece is then also in a cooling-off state and therefore no danger exists that liquid iron will dripple onto the band conveyor. Such a band conveyor requires almost no actuation forces and accepts the molds G delivered by the gridconveyor without further complication.

According to an additional embodiment of the instant invention, the conveying track may also be movable in toto transversely to the conveying direction, whereby it is movable, for example, on transverse rails relative to the form machine. In such a case, it is suitable to arrange an additional of such conveying track on these rails so that both conveying rails may be operated interchangeably, whereby more cooling time for the cast forms becomes available. This transverse movability may also be made available for one part of the conveying track, for example only for the possible available endless conveyor band.

As already mentioned above, it is an object of the invention to protect the molds G which are removed from the mold machine also on their path along the conveying track from horizontal forces which may cause a consequent displacement of the forms which have been delivered free of displacement by the forming machine. Such a consequent displacement is often caused by an incorrect placing of jackets or clamp plate arrangements. This invention includes also the support of the'mold G on the conveying track, whereby a frontal support is provided automatically when the molds G are moved onto the conveying track closely together, insofar as the transport path of the grid conveyor is adjusted to the stroke of the removal-member of the form-machine. This mutual frontal support under formation of a row of molds is schematically illustrated in FIG. 6. It is obtained by solving the balancingconditions of the mold machine in the above described manner in connection with FIG. 3. A further means for preventing a consequent displacement of horizontally divided flaskless sand molds which are pushed in close formation onto a conveying track, consists, according to the instant invention, in that the upper mold frame Ca obtains a somewhat smaller width than the lower mold frame Cb in the direction of the conveying track, so that during the placing of the molds onto the conveying track in a tight formation, the bottom mold-sections are in frontal contact with each other and that small gaps remain between the frontal sides of the upper mold halves which face each other.

In a deviation thereof, the entire molds may have frontal mutual distance of approximately 1 mm which, during the transport after the casting, are retained by means of the mold hardness and the pressure of the gases escaping out of the molds.

As above mentioned, there are means provided in a further characteristic of the invention in the area of the conveying track which accompany the molds G along their path, the means supporting at least two oppositely located lateral areas of the molds and during the placing onto the mold will automatically adapt themselves to the contours of the molds. These characteristics of the invention are disclosed in more detail in FIG. 9. FIG. 9 shows a supporting member delimiting a loadplate 21 which is placeable onto the upper side of an upper mold section Ga, and opposite thereto a further load plate 22 which is laterally slidable, and to a limited extent also upwardly and the plate 22 is provided with lateral levers 23. Vertical support plates 25 are activated on the load plate 21 by means of horizontal swivel pins 24 positioned in horizontal slots, downwardly diverging wedge pieces 26 are arranged on the outer surfaces of the support plates 25, and roller means 27 positioned at the ends of the levers 23 of the plate 22 cooperate with the wedges. Since the load plate 22 in contrast to the load plate 21, is laterally movable and the support plates 25 are pressed onto the lateral areas of the mold over the wedge pieces 26 by means of the weight of the load plate 22, and additionally these support plates, by means of the aforementioned slots, are also laterally slidably connected with the load plate 21, a subsequent displacement of the two mold sections during the placement of the support devices is also prevented when the lateral areas of the upper mold section Ga do not precisely align with the lateral areas of the lower mold section Gb.

If the molds G are not placed onto the conveying track in a tight formation in the above-mentioned manner, then support devices of the immediately abovementioned type may be utilized, which are provided with support plates 25 for all four lateral areas of the mold. The support means comprise, in this case, a type of improved jacket.

What I claim is:

1. A method of providing sand casting molds comprising providing a pattern plate having a pattern on one side thereof, positioning the pattern plate in operative relationship to a mold frame with the pattern located within the mold frame, positioning a perforated press die between the mold frame and a sand chamber located opposite the press die for vertical movement relative to the plane of the pattern plate, introducing mold sand into the sand chamber, subjecting the sane volume in the chamber to gas pressure so that the sand volume is penetrated at least from the outside with pressurized gas and begins to flow and the gas pressure causes the sand to be blasted through the perforated die into the mold frame for compacting the sand about the pattern, moving the perforated die towards the pattern plate for re-compacting the sand, releasing the finished mold, and moving the finished mold to a casting pit and a knock-out point by a conveying track.

2. The method of providing sand casting molds as claimedin claim 1 including-forcing a part of the sand filling blasted into the mold frame back through the v perforated press die into the sand chamber during the 3. The method of providing sand casting molds as claimed in claim 2 in which the sand volume in the chamber is additionally penetrated with pressurized gas from the inside.

4. The method of providing sand casting molds as claimed in claim 2 in which the sand blasted into the mold frame is penetrated with pressurized gas during re-compacting of the sand.

5. The method of providing sand casting molds as claimed in claim 2 including said subjecting the sand volume in the chamber to gas pressure being performed in two stages, the first stage comprising said penetration of said sand volume with pressurized gas and the second stage comprising mainly additional superficial subjection of said sand volume by the gas pressure to move it through the perforations of the press die into the mold frame.

6. The method of providing sand casting molds as claimed in claim 5 including overlapping the first and second gas pressure stages.

- 7. The method of providing sand casting molds as claimed in claim 1 including moving the finished molds along the conveying track by force impulses being directed generally horizontal in the conveying direction, with the impulses each effecting intermittently the molds via friction over partial areas of the mold surface thereby at least overcoming the friction between the mold bottom areas and support areas of the conveying track.

8. A method of providing horizontally divided flaskless sand molds, comprising introducing a match plate having a pattern on each side between two mold frames and perforated press dies of a mold making machine actuatable in a substantially vertical direction, lowering the upper mold frame and raising the lower mold frame to cooperate with the match plate for forming mold cavities on each side of the match plate, locating a sand chamber oppositeeach press die, subjecting the sand volume in each chamber to gas pressure so that the sand volume is penetrated at least from the outside with pressurized gas and begins to flow, and the gas pressure causes the sand to be blasted through the perforated die into the mold cavity for compacting the sand about the pattern, re-compacting the sand against the match plate by moving the dies relative to the mold frames, raising and lowering the upper mold frame and die and the lower mold frame and die respectively to free and move the match plate away, closing the mold by lowering and raising the upper mold frame and die and the lower mold frame and die, releasing the finished mold, and moving the finished mold to a casting pit and a knock-out point by a conveyor track.

9. The method of providing sand casting molds with at least one core as claimed in claim 8 in which prior to closing of the mold, includes moving the lower part thereof from the operational area of the mold frame, inserting the core, and moving the lower part into the operational area of the mold frame.

10. The method of providing sand casting molds with at least one core as claimed in claim 8 in which prior to closing of the mold, includes moving an identical lower part having a core into the operational area of the mold frame.

11. The method of providing sand casting molds as claimed in claim 8 comprising defining a mold train on the conveyor track and spacing the front areas of the molds in the mold train apart by about 0.5 mm to 1 mm and maintaining such spacing by the mold hardness and the pressure of the gases leaving the mold.

12. The method of providing sand casting molds as claimed in claim 8 comprising defining a mold train on the conveyor track and engaging the front areas of the bottom halves of the molds in the mold train and separating the front areas of the upper halves of the molds located thereabove from each other by about 0.5 mm to 1 mm.

13. The method of-providing sand casting molds as claimed in claim 1 comprising applying mechanical surface pressures to the respective upper areas and at least two oppositely directed lateral areas of the mold located on the conveying track, whereby the surface pressures adapt themselves to the shape of such areas.

14. The method of providing sand casting molds as claimed in claim 8 comprising applying mechanical surface pressures to the respective upper areas and at least two oppositely directed lateral areas of the mold located on the conveying track, whereby the surface pressures adapt themselves to the shape of such areas, the surface pressures being distributed over the upper and lower parts of the mold so that any horizontal components developing are insufficient to cause a displacement of the mold parts.

15. An apparatus for providing sand casting molds, comprising at least one mold frame, at least one pattern plate having a pattern on one side thereof cooperable with the mold frame so that the pattern provides a molding cavity within the mold frame, at least one perforated press die cooperable with the mold frame and movable vertically relative to the plane of the pattern plate a mold sand chamber positioned opposite the press die, means for introducing sand into the chamber,

and pneumatic means operably related to the sand chamber for supplying pressurized gas into the chamber in a controlled manner for causing the sand to begin to flow and for moving the sand from the chamber through the perforated press die into the molding cavity within the mold frame for compacting the sand about the pattern, the pneumatic means including at least one gas chamber surrounding the sand chamber, a pipe for pressurized gas communicating with the gas chamber, means providing communication between the gas chamber and the interior of the sand chamber, said pipe serving for a prompt superficial loading and effecting a penetration of the sand volume with pressurized gas, the perforated die being movable toward the patternplate for re-compacting the sand, means for releasing the finished mold, and a conveyor track for moving the finished mold to a casting pit and knock-out point.

16. The apparatus for providing sand casting molds as claimed in claim in which the press die is defined by a grid for the mold sand.

17. The apparatus for providing sand casting molds as claimed in claim 16 in which the spaces between the grid bars are at least 35 mm in width.

18. The apparatus for providing sand casting molds as claimed in claim 16 further including transverse pipes located within the sand chamber, the transverse pipes having openings and the pipes being connected with the gas chamber, the means providing communication between the gas chamber and the sand chamber being openings, and shutters cooperable with the openings of the transverse pipes and the openings of the gas chamber for guiding the pressurized gas flow in a predetermined direction and preventing the sand in the sand chamber from entering the transverse pipes and gas chamber.

19. An apparatus for providing sand casting molds, comprising at least one mold frame, at lease one pattern plate having a pattern on one side thereof cooperable with the mold frame so that the pattern provides a molding cavity within the mold frame, at least one perforated press die cooperable with the mold frame and movable vertically relative to the plane of the pattern plate, a mold sand chamber positioned opposite the press die, means for introducing sand into the chamber, and pneumatic means operably related to the sand chamber for supplying pressurized gas into the chamber in a controlled manner for causing the sand to begin to flow and for moving the sand from the chamber through the perforated press die into the molding cavity within the mold frame for compacting the sand about the pattern, the pneumatic means including first and second gas chambers surrounding the upper and lower areas of the sand chamber, a first pipe of a large diameter for pressurized gas communicating with the first gas chamber, a second pipe of smaller diameter for pressurized gas communicating with the second gas chamber, means providing communication between the first and second gas chambers and the interior of the sand chamber, said first pipe serving for a prompt excess loading of the sand volume within the sand chamber with pressurized gas, and said second pipe serving for effecting a penetration of the sand volume with pressurized gas, the perforated die being movable toward the pattern plate for re-compacting the sand, means for releasing the finished mold, and a conveyor track for moving the finished mold to a casting pit and knock-out point.

20. The apparatus for providing sand casting molds as claimed in claim 15 in which the press die includes two parallel laterally slidable interconnected discs, the rim of the disc facing the mold frame space being slidingly guided in the mold frame and the rim of the disc facing the sand chamber being provided with lateral play towards the mold frame.

21. The apparatus for providing sand casting molds as claimed in claim 15 in which the rim of the mold frame facing the pattern plate and the rim of the pattern plate facing the mold frame include complemental surfaces enabling the rim of the mold frame to slide sealingly over the rim of the pattern plate during placement of the mold frame on the pattern plate.

22. The apparatus for providing sand casting molds as claimed in claim 21 in which at least one abutment which cooperates with the rim of the mold frame facing the pattern plate is arranged on the edge of the pattern plate, with the abutment insuring that the edge of the mold frame and the pattern plate area facing the mold frame are positioned on an even plane.

23. An apparatus for providing horizontally divided flaskless sand molds, comprising substantially vertically movable upper and lower mold frames, upper and lower perforated press dies respectively contained in the mold frames and capable of relative movement thereto, a match plate having patterns on the top and bottom surfaces thereof mounted for movement from a rest position laterally adjacent the apparatus to an operative position between the mold frames and dies, a sand chamber located above the upper press die, a sand chamber located below the lower press die, a mold sand tank operably connected to the sand chambers, and an installation including control means for supplying pressurized gas to the sand chambers for penetrating the sand therein and for moving sand through the perforated dies into the mold frames, said lower mold frame being laterally movable from its working position to a second position outside the working position.

24. The apparatus for providing horizontally divided flaskless sand molds as claimed in claim 23, including two lower mold frames, and means interconnecting the two lower mold frames in substantially diametrically opposed relationship so that with one lower mold frame in the working position, the other lower mold frame is in the second position.

25. An apparatus for providing sand casting molds as claimed in claim 24, in which the installation with control means for supplying pressurized gas to the sand chambers for causing the sand to begin to flow and for moving the sand from the sand chambers through the perforated press dies into the molding cavities within the mold frames for compacting the sand about the patterns include gas chambers surrounding the sand chambers, at least one pipe for pressurized gas communicating with the gas chambers, means providing communication between the gas chambers and the interiors of the sand chambers, said pipe and communication means serving for a prompt superficial loading of the sand volumes within the sand chambers and effecting a penetration of the sand volumes within the sand chambers with pressurized gas.

26. The apparatus for providing sand casting molds as claimed in claim 25 further including transverse pipes located within the sand chambers, the transverse pipes having openings and the pipes being connected with the gas chambers, the means providing communication between the gas chambers and the sand chambers being openings, and shutters cooperable with the openings of the transverse pipes and the openings of the gas chambers for guiding the pressurized gas flow in a predetermined direction and preventing the sand in the sand chambers from entering the transverse pipes and gas chambers.

27. The apparatus for providing sand casting molds as claimed in claim 15 in which the conveyor track is provided with at least one section including grid bars, certain of the grid bars executing backward and forward movements in the direction of conveying, with such bars being strongly urged against the bottom areas of the molds so that the friction developing between such bars and the molds is greater than the friction existing between the other bars and the molds, such grid bars receiving an impulse directed away from the bottom areas before counter movement to the conveying movement, and the impulse being such that the friction existing between such grid bars and the molds becomes at least less than the friction existing between the other grid bars and the molds. 1

28. The apparatus for providing sand casting molds as claimed in claim 27, including a non-activated band conveyor placed after said at least one section of the conveyor track.

29. The apparatus for providing sand casting molds as claimed in claim 27 in which at least one part of the conveyor track is transversely movable in the conveying direction relative to the apparatus.

30. The apparatus for providing sand casting molds as claimed in claim 15 including means accompanying the molds along the conveyor track, said means supporting at least two opposite lateral areas of the molds and during placement onto the molds automatically adapt to the contours of the molds.

31. The apparatus for providing sand casting molds as claimed in claim 30in which said supporting means includes a load plate positioned on the upper side of the mold, at least two oppositely positioned vertical support plates, a hinge connection between each vertical support plate and said load platefdefined by horizontal slots in said load plate and horizontal pins on said vertiforcing the support plates in the direction of the side areas of the mold.

32. The apparatus for providing sand casting molds as claimed in claim 23 including a conveyor track adjacent the apparatus and receiving the finished molds from the apparatus and conveying them to the casting pit and to the knock-out point.

33. The apparatus for providing sand casting molds as claimed in claim 32 in which the conveyor track is provided with at least one section including grid bars, certain of the grid bars executing backward and forward movements in the direction of conveying, with such bars being strongly urged against the bottom areas of the molds so that the friction developing between such bars and the molds is greater than the friction existing between the other bars and the molds, such grid bars receiving an impulse directed away from the bottom areas before counter movement to the conveying movement, and the impulse being such that the friction existing between such grid bars and the molds becomes less than the friction existing between the other grid bars and the molds.

34. The apparatus for providing sand casting molds as claimed in claim 33, including a non-activated band conveyor placed after said at least one section of the conveyor track.

35. The apparatus for providing sand casting molds as claimed in claim 33 in which at least one part of the conveyor track is transversely movable in the conveying direction relative to the apparatus.

' 36. The apparatus for producing sand casting molds as claimed in claim 33 including means accompanying the molds along the conveyor track, said means supporting at least two opposite lateral areas of the molds and during placement onto themolds automatically adapt to.the contours of the molds, said supporting means including a load plate positioned on the upper side of the mold, at least two oppositely positioned vertical support plates, a hinge connection between each vertical support plate and said load plate defined by horizontal slots in said load plate and horizontal pins on cal support plates lodged in said slots, and a second said vertical support plates lodged in said slots, and a second load plate above said load plate, said second load plate being laterally slidable and capable of limited upward movement relative to said load plate, said second load plate having a lever at each end thereof overlapping each vertical support plate, and a wedge on each vertical support plate with which the levers cooperate for forcing the support plates in the direction of the side areas of the mold. 

1. A method of providing sand casting molds comprising providing a pattern plate having a pattern on one side thereof, positioning the pattern plate in operative relationship to a mold frame with the pattern located within the mold frame, positioning a perforated press die between the mold frame and a sand chamber located opposite the press die for vertical movement relative to the plane of the pattern plate, introducing mold sand into the sand chamber, subjecting the sane volume in the chamber to gas pressure so that the sand volume is penetrated at least from the outside with pressurized gas and begins to flow and the gas pressure causes the sand to be blasted through the perforated die into the mold frame for compacting the sand about the pattern, moving the perforated die towards the pattern plate for recompacting the sand, releasing the finished mold, and moving the finished mold to a casting pit and a knock-out point by a conveying track.
 2. The method of providing sand casting molds as claimed in claim 1 including forcing a part of the sand filling blasted into the mold frame back through the perforated press die into the sand chamber during the re-compacting of the sand by the movement of the press die.
 3. The method of providing sand casting molds as claimed in claim 2 in which the sand volume in the chamber is additionally penetrated with pressurized gas from the inside.
 4. The method of providing sand casting molds as claimed in claim 2 in which the sand blasted into the mold frame is penetrated with pressurized gas during re-compacting of the sand.
 5. The method of provIding sand casting molds as claimed in claim 2 including said subjecting the sand volume in the chamber to gas pressure being performed in two stages, the first stage comprising said penetration of said sand volume with pressurized gas and the second stage comprising mainly additional superficial subjection of said sand volume by the gas pressure to move it through the perforations of the press die into the mold frame.
 6. The method of providing sand casting molds as claimed in claim 5 including overlapping the first and second gas pressure stages.
 7. The method of providing sand casting molds as claimed in claim 1 including moving the finished molds along the conveying track by force impulses being directed generally horizontal in the conveying direction, with the impulses each effecting intermittently the molds via friction over partial areas of the mold surface thereby at least overcoming the friction between the mold bottom areas and support areas of the conveying track.
 8. A method of providing horizontally divided flaskless sand molds, comprising introducing a match plate having a pattern on each side between two mold frames and perforated press dies of a mold making machine actuatable in a substantially vertical direction, lowering the upper mold frame and raising the lower mold frame to cooperate with the match plate for forming mold cavities on each side of the match plate, locating a sand chamber opposite each press die, subjecting the sand volume in each chamber to gas pressure so that the sand volume is penetrated at least from the outside with pressurized gas and begins to flow, and the gas pressure causes the sand to be blasted through the perforated die into the mold cavity for compacting the sand about the pattern, re-compacting the sand against the match plate by moving the dies relative to the mold frames, raising and lowering the upper mold frame and die and the lower mold frame and die respectively to free and move the match plate away, closing the mold by lowering and raising the upper mold frame and die and the lower mold frame and die, releasing the finished mold, and moving the finished mold to a casting pit and a knock-out point by a conveyor track.
 9. The method of providing sand casting molds with at least one core as claimed in claim 8 in which prior to closing of the mold, includes moving the lower part thereof from the operational area of the mold frame, inserting the core, and moving the lower part into the operational area of the mold frame.
 10. The method of providing sand casting molds with at least one core as claimed in claim 8 in which prior to closing of the mold, includes moving an identical lower part having a core into the operational area of the mold frame.
 11. The method of providing sand casting molds as claimed in claim 8 comprising defining a mold train on the conveyor track and spacing the front areas of the molds in the mold train apart by about 0.5 mm to 1 mm and maintaining such spacing by the mold hardness and the pressure of the gases leaving the mold.
 12. The method of providing sand casting molds as claimed in claim 8 comprising defining a mold train on the conveyor track and engaging the front areas of the bottom halves of the molds in the mold train and separating the front areas of the upper halves of the molds located thereabove from each other by about 0.5 mm to 1 mm.
 13. The method of providing sand casting molds as claimed in claim 1 comprising applying mechanical surface pressures to the respective upper areas and at least two oppositely directed lateral areas of the mold located on the conveying track, whereby the surface pressures adapt themselves to the shape of such areas.
 14. The method of providing sand casting molds as claimed in claim 8 comprising applying mechanical surface pressures to the respective upper areas and at least two oppositely directed lateral areas of the mold located on the conveying track, whereby the surface pressures adapt themselves to the shApe of such areas, the surface pressures being distributed over the upper and lower parts of the mold so that any horizontal components developing are insufficient to cause a displacement of the mold parts.
 15. An apparatus for providing sand casting molds, comprising at least one mold frame, at least one pattern plate having a pattern on one side thereof cooperable with the mold frame so that the pattern provides a molding cavity within the mold frame, at least one perforated press die cooperable with the mold frame and movable vertically relative to the plane of the pattern plate a mold sand chamber positioned opposite the press die, means for introducing sand into the chamber, and pneumatic means operably related to the sand chamber for supplying pressurized gas into the chamber in a controlled manner for causing the sand to begin to flow and for moving the sand from the chamber through the perforated press die into the molding cavity within the mold frame for compacting the sand about the pattern, the pneumatic means including at least one gas chamber surrounding the sand chamber, a pipe for pressurized gas communicating with the gas chamber, means providing communication between the gas chamber and the interior of the sand chamber, said pipe serving for a prompt superficial loading and effecting a penetration of the sand volume with pressurized gas, the perforated die being movable toward the pattern plate for re-compacting the sand, means for releasing the finished mold, and a conveyor track for moving the finished mold to a casting pit and knock-out point.
 16. The apparatus for providing sand casting molds as claimed in claim 15 in which the press die is defined by a grid for the mold sand.
 17. The apparatus for providing sand casting molds as claimed in claim 16 in which the spaces between the grid bars are at least 35 mm in width.
 18. The apparatus for providing sand casting molds as claimed in claim 16 further including transverse pipes located within the sand chamber, the transverse pipes having openings and the pipes being connected with the gas chamber, the means providing communication between the gas chamber and the sand chamber being openings, and shutters cooperable with the openings of the transverse pipes and the openings of the gas chamber for guiding the pressurized gas flow in a predetermined direction and preventing the sand in the sand chamber from entering the transverse pipes and gas chamber.
 19. An apparatus for providing sand casting molds, comprising at least one mold frame, at lease one pattern plate having a pattern on one side thereof cooperable with the mold frame so that the pattern provides a molding cavity within the mold frame, at least one perforated press die cooperable with the mold frame and movable vertically relative to the plane of the pattern plate, a mold sand chamber positioned opposite the press die, means for introducing sand into the chamber, and pneumatic means operably related to the sand chamber for supplying pressurized gas into the chamber in a controlled manner for causing the sand to begin to flow and for moving the sand from the chamber through the perforated press die into the molding cavity within the mold frame for compacting the sand about the pattern, the pneumatic means including first and second gas chambers surrounding the upper and lower areas of the sand chamber, a first pipe of a large diameter for pressurized gas communicating with the first gas chamber, a second pipe of smaller diameter for pressurized gas communicating with the second gas chamber, means providing communication between the first and second gas chambers and the interior of the sand chamber, said first pipe serving for a prompt excess loading of the sand volume within the sand chamber with pressurized gas, and said second pipe serving for effecting a penetration of the sand volume with pressurized gas, the perforated die being movable toward the pattern plate for re-compacting the sand, means for releasing the finished Mold, and a conveyor track for moving the finished mold to a casting pit and knock-out point.
 20. The apparatus for providing sand casting molds as claimed in claim 15 in which the press die includes two parallel laterally slidable interconnected discs, the rim of the disc facing the mold frame space being slidingly guided in the mold frame and the rim of the disc facing the sand chamber being provided with lateral play towards the mold frame.
 21. The apparatus for providing sand casting molds as claimed in claim 15 in which the rim of the mold frame facing the pattern plate and the rim of the pattern plate facing the mold frame include complemental surfaces enabling the rim of the mold frame to slide sealingly over the rim of the pattern plate during placement of the mold frame on the pattern plate.
 22. The apparatus for providing sand casting molds as claimed in claim 21 in which at least one abutment which cooperates with the rim of the mold frame facing the pattern plate is arranged on the edge of the pattern plate, with the abutment insuring that the edge of the mold frame and the pattern plate area facing the mold frame are positioned on an even plane.
 23. An apparatus for providing horizontally divided flaskless sand molds, comprising substantially vertically movable upper and lower mold frames, upper and lower perforated press dies respectively contained in the mold frames and capable of relative movement thereto, a match plate having patterns on the top and bottom surfaces thereof mounted for movement from a rest position laterally adjacent the apparatus to an operative position between the mold frames and dies, a sand chamber located above the upper press die, a sand chamber located below the lower press die, a mold sand tank operably connected to the sand chambers, and an installation including control means for supplying pressurized gas to the sand chambers for penetrating the sand therein and for moving sand through the perforated dies into the mold frames, said lower mold frame being laterally movable from its working position to a second position outside the working position.
 24. The apparatus for providing horizontally divided flaskless sand molds as claimed in claim 23, including two lower mold frames, and means interconnecting the two lower mold frames in substantially diametrically opposed relationship so that with one lower mold frame in the working position, the other lower mold frame is in the second position.
 25. An apparatus for providing sand casting molds as claimed in claim 24, in which the installation with control means for supplying pressurized gas to the sand chambers for causing the sand to begin to flow and for moving the sand from the sand chambers through the perforated press dies into the molding cavities within the mold frames for compacting the sand about the patterns include gas chambers surrounding the sand chambers, at least one pipe for pressurized gas communicating with the gas chambers, means providing communication between the gas chambers and the interiors of the sand chambers, said pipe and communication means serving for a prompt superficial loading of the sand volumes within the sand chambers and effecting a penetration of the sand volumes within the sand chambers with pressurized gas.
 26. The apparatus for providing sand casting molds as claimed in claim 25 further including transverse pipes located within the sand chambers, the transverse pipes having openings and the pipes being connected with the gas chambers, the means providing communication between the gas chambers and the sand chambers being openings, and shutters cooperable with the openings of the transverse pipes and the openings of the gas chambers for guiding the pressurized gas flow in a predetermined direction and preventing the sand in the sand chambers from entering the transverse pipes and gas chambers.
 27. The apparatus for providing sand casting molds as claimed in claim 15 in which the conveyor track is provided with at least one seCtion including grid bars, certain of the grid bars executing backward and forward movements in the direction of conveying, with such bars being strongly urged against the bottom areas of the molds so that the friction developing between such bars and the molds is greater than the friction existing between the other bars and the molds, such grid bars receiving an impulse directed away from the bottom areas before counter movement to the conveying movement, and the impulse being such that the friction existing between such grid bars and the molds becomes at least less than the friction existing between the other grid bars and the molds.
 28. The apparatus for providing sand casting molds as claimed in claim 27, including a non-activated band conveyor placed after said at least one section of the conveyor track.
 29. The apparatus for providing sand casting molds as claimed in claim 27, in which at least one part of the conveyor track is transversely movable in the conveying direction relative to the apparatus.
 30. The apparatus for providing sand casting molds as claimed in claim 15 including means accompanying the molds along the conveyor track, said means supporting at least two opposite lateral areas of the molds and during placement onto the molds automatically adapt to the contours of the molds.
 31. The apparatus for providing sand casting molds as claimed in claim 30 in which said supporting means includes a load plate positioned on the upper side of the mold, at least two oppositely positioned vertical support plates, a hinge connection between each vertical support plate and said load plate defined by horizontal slots in said load plate and horizontal pins on said vertical support plates lodged in said slots, and a second load plate above said load plate, said second load plate being laterally slidable and capable of limited upward movement relative to said load plate, said second load plate having a lever at each end thereof overlapping each vertical support plate, and a wedge on each vertical support plate with which the levers cooperate for forcing the support plates in the direction of the side areas of the mold.
 32. The apparatus for providing sand casting molds as claimed in claim 23 including a conveyor track adjacent the apparatus and receiving the finished molds from the apparatus and conveying them to the casting pit and to the knock-out point.
 33. The apparatus for providing sand casting molds as claimed in claim 32 in which the conveyor track is provided with at least one section including grid bars, certain of the grid bars executing backward and forward movements in the direction of conveying, with such bars being strongly urged against the bottom areas of the molds so that the friction developing between such bars and the molds is greater than the friction existing between the other bars and the molds, such grid bars receiving an impulse directed away from the bottom areas before counter movement to the conveying movement, and the impulse being such that the friction existing between such grid bars and the molds becomes less than the friction existing between the other grid bars and the molds.
 34. The apparatus for providing sand casting molds as claimed in claim 33, including a non-activated band conveyor placed after said at least one section of the conveyor track.
 35. The apparatus for providing sand casting molds as claimed in claim 33 in which at least one part of the conveyor track is transversely movable in the conveying direction relative to the apparatus.
 36. The apparatus for producing sand casting molds as claimed in claim 33 including means accompanying the molds along the conveyor track, said means supporting at least two opposite lateral areas of the molds and during placement onto the molds automatically adapt to the contours of the molds, said supporting means including a load plate positioned on the upper side of the mold, at least two oppositely positioned vertical support plates, a hinge connection between each vertiCal support plate and said load plate defined by horizontal slots in said load plate and horizontal pins on said vertical support plates lodged in said slots, and a second load plate above said load plate, said second load plate being laterally slidable and capable of limited upward movement relative to said load plate, said second load plate having a lever at each end thereof overlapping each vertical support plate, and a wedge on each vertical support plate with which the levers cooperate for forcing the support plates in the direction of the side areas of the mold. 